Compound semiconductor products have been used in emitting diodes for displays, optical telecommunications equipment, laser diodes (LD) for compact/video discs (CD/VD), photoconductors, capacitors for high speed computers, capacitors for satellites, and the like. The use of compound semiconductor products is being extendeded to mobile telecommunications equipment, blue laser diodes for optical digital displays (ODD), capacitors for optical computers, and the like.
Light emitting diodes (LED) used for color image, graphic display elements provide a full color display through a combination of the three basic colors, red, green and blue. Among these, blue LED is manufactured from III-V nitrides, AIN, GaN, InN, and the like, and have emitting wavelengths of about 450 nm. (Al.sub.x Ga.sub.1- x).sub.1- y In.sub.y N has a direct energy band structure in the range of (1.gtoreq.x .gtoreq.0) and (1.gtoreq.y.gtoreq.0), and has the advantage of adjusting the band gap from 2.0 eV up to 6.2 eV (wavelength range, 370-650 nm) with the variations in x and y variables providing the ability to realize various colors with a single material.
Metal Organic Chemical Vapor Deposition (MOCVD) systems are generally used in processing III nitride materials. MOCVD systems are divided into two basic groups by the arrangement of the reactor types, horizontal reactors and vertical reactors.
Vertical reactors are generally equipped with a rotating mechanism for susceptors and are inferior in terms of uniformity in epitaxial growth due to a speedy flow of source gases on the periphery of the substrate. In contrast, horizontal reactors are advantageous for obtaining uniformity due to laminar flow formation of source gases parallel with the substrate. In spite of this, conventional horizontal reactors are still weak in suppressing thermal convection resulting in limitations on the formation of a uniform epitaxial growth. Although horizontal reactors employing rotating suceptors for improving uniformity are known, they have the disadvantage of producing dust from gear friction and insufficient prevention of thermal convection even with the employment of such rotating mechanisms.
Prior art publications for GaN based semiconductor processing techniques include T. Nakamori, Nikkei Electronics Asia, 6(1), 57(1997); M. Kamp, Compound Semiconductor, 2(5), 22 (1996); I. Bhat, Compound Semiconductor, 2(5), 24(1996); S. Nakamura, Microelectronics, J., 25(8), 651 1994); and S. Strite and H. Morkoc, J. Vac. Sci. Technol., R10(4), 1237(1992).